This Is Why You Should Never, Ever Refill Your Plastic Water Bottle

We’re all guilty — but the consequences can be seriously harmful for your health.

Most of us don’t think twice about refilling our plastic water bottles. After all, it’s all in the name of personal hydration—plus, it’s eco-friendly! And there’s absolutely nothing harmful about a simple bottle of water, right?

Wrong! That plastic water bottle could actually do your body more harm than good, experts say. Why? You can thank Biphenol A (commonly known as BPA), a chemical used to manufacture plastics, for your water woes. This harmful chemical can leach into the water and quickly grow dangerous bacteria in the bottle’s cracks. (It’s why you should stay away from straws, too.) And the health consequences are pretty serious.

“Certain chemicals found in plastic bottles can have effects on every system in our bodies,’ Dr. Marilyn Glenville told Good Housekeeping UK. “They can affect ovulation, and increase our risk of hormonally driven problems like PCOS, endometriosis and breast cancer, among other things.”

Science just proved it, too! In a study conducted by Treadmill Reviews, researchers tested water bottles used by athletes for a week and found that the bacteria count reached over 900,000 colony-forming units per square centimeter, on average. Get this: That’s more bacteria than the average toilet seat. Plus, 60 percent of those germs were able to make people sick. Gross!

To hydrate without harm, smart drinkers should avoid re-using disposable bottles. Instead, you should recycle them after drinking up once; or, better yet, invest in a BPA-free plastic bottle or one made from glass or stainless steel. Not only will doing so benefit your health, but you can help the environment, too.